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1.
Modulus of subgrade reaction is one of the required design parameters in any structural analyses of shallow foundations. However, the constant values of modulus of subgrade reaction that are determined from either from literature studies or the results of plate load tests, regardless of magnitude of soil’s displacement under design loads, have been used in structural designs of foundations. In this study, the results of 43 published full-scale field plate load tests in cohesionles soils were gathered to expose any variation in the values of modulus of subgrade reaction as soil’s displacement increases. Extensive finite element (FE) analyses were carried out while the results of FE analyses were compared with actual measured results of field load tests. The results of analyses indicated that both the modulus of subgrade reaction decrease with increase in magnitude of displacement of soils and internal forces of a design of structural frame is higher with the values of modulus of subgrade reaction that are sensitive to soil’s displacement are implemented into analyses. Therefore, structural dimensions of any structure with the constant values of modulus of subgrade reaction would not be a precise engineering solution. 相似文献
2.
This paper presents probable effects of climate change on soil moisture availability in the Southeast Anatolia Development Project (GAP) region of Turkey. A series of hypothetical climate change scenarios and GCM-generated IPCC Business-as-Usual scenario estimates of temperature and precipitation changes were used to examine implications of climate change for seasonal changes in actual evapotranspiration, soil moisture deficit, and soil moisture surplus in 13 subregions of the GAP. Of particular importance are predicted patterns of enhancement in summer soil moisture deficit that are consistent across the region in all scenarios. Least effect of the projected warming on the soil moisture deficit enhancement is observed with the IPCC estimates. The projected temperature changes would be responsible for a great portion of the enhancement in summer deficits in the GAP region. The increase in precipitation had less effect on depletion rate of soil moisture when the temperatures increase. Particularly southern and southeastern parts of the region will suffer severe moisture shortages during summer. Winter surplus decreased in scenarios with increased temperature and decreased precipitation in most cases. Even when precipitation was not changed, total annual surplus decreased by 4 percent to 43 percent for a 2°C warming and by 8 percent to 91 percent for a 4°C warming. These hydrologic results may have significant implications for water availability in the GAP as the present project evaluations lack climate change analysis. Adaptation strategies – such as changes in crop varieties, applying more advanced dry farming methods, improved water management, developing more efficient irrigation systems, and changes in planting – will be important in limiting adverse effects and taking advantage of beneficial changes in climate. 相似文献
3.
Spectral and Spatial Quality Analysis in Pan Sharpening Process 总被引：1，自引：0，他引：1
Image fusion is a process to obtain new images containing more information by combining images obtained same or different sensors. With most of the earth observation satellites, high spatial resolution panchromatic images and low spatial resolution multispectral images are obtained. As an example of image fusion ??pan sharpening?? is a process of combining of high spatial resolution panchromatic images and low spatial resolution multispectral images. At the end of the fusion process both high spatial and spectral resolution new images are obtained. In this study, panchromatic and multispectral images gathered from Ikonos were used. Panchromatic and multispectral images belonging to the same sensor were combined by using different image fusion methods. As pan sharpening methods Brovey transform, Modified IHS, Principal Component Analysis (PCA), Wavelet PC transform and Wavelet A Trous transformation methods were used. Quality of fused products was evaluated from the point of view of both visual and statistical criteria. While wavelet based methods are succesfull in terms of protection of spectral quality of original multispectral images, the colorbased and statistical methods are giving better results within the improvement of spatial content. 相似文献
4.
In this study, it was aimed to determine the effect of various aeration rates on composting to supply the optimum aeration rate for a successful and economic composting. For this aim, vegetable–fruit wastes (VFW) were composted at various aeration rates (0.37, 0.49, 0.62, 0.74, 0.86, and 0.99 L/min kg VS) and moisture, temperature, pH, electrical conductivity, C/N, and cellulose were investigated. Moistures of the reactor that had the highest aeration were generally lower than those of the others. Reactor that had the lowest aeration reached thermophilic phase earlier than the others and stayed more days. This situation was opposite for the reactor that had the highest aeration. pH variations with aeration rates were not significant. Although electrical conductivity did not differ significantly with aeration rates, at the beginning of the thermophilic phase it generally increased with the increase in aeration. The highest C/N reduction was observed in the reactor that had an aeration of 0.62 L/min kg VS. The final cellulose contents were close to each other. It could be said that aeration rates used were efficient on composting of VFW. Taking the C/N into account which is the parameter of the indicator of the stabilization in composting, it could be said that the optimum aeration rate for forced aerobic composting of VFW was 0.62 L/min kg VS. 相似文献
5.
In Hungary four extensometric observatories were established in the last two decades. The extensometers were installed primarily for observations of Earth tides. A 15-year continuous data series (1991–2005) was recorded at the Sopronbánfalva station and a 7-year record (1993–1999) was obtained at the Pécs station. The length of the measured continuous data series at the two other stations (Bakonya and Budapest) is only a few years. The long-term data records were also applied to the investigation of long-periodic deformations caused by recent tectonic movements. To get an insight into the present day tectonic processes on the margin of the Pannonian Basin, the measurement results of two additional stations (Vyhne in Slovakia and Beregovo in Ukraine) were also included into the investigations. The seasonal variations in the long data series due to temperature and air pressure effects were eliminated. The residual curve – after the correction of the seasonal effects and filtering the “high frequency” components (e.g. earthquakes, Earth tides, etc.) – contains the instrumental drift. It is impossible to determine this curve mathematically. It can be diminished by special instrumental solutions and by regular calibration of the instruments. This paper shows methods and possible solutions how the instrumental drift was investigated and eliminated in order to get the most reliable data for studying recent tectonic movements. The reliability of the extensometric measurements was tested by the tidal evaluation of the data series. The results of the observations show that the Pannonian Basin is under compressive stress. The strain rates measured by extensometers on the margin of the basin are about three orders of magnitude higher than the intra-plate strains obtained by GPS measurements. The reason for this large difference arises from the interaction between the plate boundary and intra-plate forces and from the different measurement techniques. Investigations showed that the rate of the tectonic movements varies, and depends on the local geographical and topographical conditions. 相似文献
6.
Bengt G. Martinsson Göran Frank Sven&#;Inge Cederfelt Olle H. Berg Besim Mentes Giorgos Papaspiropoulos Erik Swietlicki Jingchuan Zhou Michael Flynn Keith N. Bower Tom W. Choularton Jyrki Mäkelä Aki Virkkula Rita Van Dingenen 《Tellus. Series B, Chemical and physical meteorology》2000,52(2):801-814
The microstructure of orographic clouds related to the aerosol present was studied during the second Aerosol Characterisation Experiment (ACE‐2). Very high cloud droplet number concentrations (almost 3000 cm−3 ) were observed. These high concentrations occurred when clouds formed on a hill slope at Tenerife in polluted air masses originating in Europe that had transported the order of 1000 km over the Atlantic Ocean. The validity of the measured droplet number concentrations was investigated by comparing with measurements of the aerosol upstream of the cloud and cloud interstitial aerosol. Guided by distributions of the ratios between the measurements, three criteria of typically 30% in maximum deviation were applied to the measurements to test their validity. Agreement was found for 88% of the cases. The validated data set spans droplet number concentrations of 150–3000 cm−3 . The updraught velocity during the cloud formation was estimated to 2.2 m s−1 by model calculations, which is typical of cumuliform clouds. The results of the present study are discussed in relation to cloud droplet number concentrations previously reported in the literature. The importance of promoting the mechanistic understanding of the aerosol/cloud interaction and the use of validation procedures of cloud microphysical parameters is stressed in relation to the assessment of the indirect climatic effect of aerosols. 相似文献
7.
M. E. Ayhan 《Journal of Geodesy》1997,71(6):362-369
In the analyses of 2D real arrays, fast Hartley (FHT), fast T (FTT) and real-valued fast Fourier transforms are generally
preferred in lieu of a complex fast Fourier transform due to the advantages of the former with respect to disk storage and
computation time. Although the FHT and the FTT in one dimension are identical, they are different in two or more dimensions.
Therefore, first, definitions and some properties of both transforms and the related 2D FHT and FTT algorithms are stated.
After reviewing the 2D FHT and FTT solutions of Stokes' formula in planar approximation, 2D FHT and FTT methods are developed
for geoid updating to incorporate additional gravity anomalies. The methods are applied for a test area which includes a 64×64
grid of 3′×3′ point gravity anomalies and geoid heights calculated from point masses. The geoids computed by 2D FHT and FTT are found to
be identical. However, the RMS value of the differences between the computed and test geoid is ±15 mm. The numerical simulations
indicate that the new methods of geoid updating are practical and accurate with considerable savings on storage requirements.
Received: 15 February 1996; Accepted: 22 January 1997 相似文献
8.
A model for the conservation of geological remains as documents 总被引：1，自引：0，他引：1
Geological remains are conserved mainly either together with living beings for the sake of the integrity of nature or for
their economical or aesthetic value. However, they also have scientific value for the geologist to reconstruct the earth's
past. For this reason we propose a model which is an application of marginal utility theory in economics and takes into account
the informational utility of geological remains. Informational utility of geological remains ranges over their geological significance which is induced by the importance of the geological processes that produce them, and over their spatial extensiveness. Our model takes into account also the cost and budget of conservation and proposes to solve the differential equations of informational utility and cost simultaneously in order
to obtain the optimum quantity of the remains to be conserved.
Received: 9 January 1998 · Accepted: 4 February 1998 相似文献
9.
uayip Küpeli M. Muzaffer Karadag Ahmet Ayhan Adnan Dyen Fetullah Ar&#x;k 《Chemie der Erde / Geochemistry》2007,67(4):313-322
The Attepe district consists of Precambrian, Lower–Middle Cambrian, Upper Cambrian–Lower Ordovician and Mesozoic formations. It contains several iron deposits and occurrences. Three types of iron-mineralizations can be distinguished in the area; (i) Sedimentary Fe-sulfide in Precambrian bituminous metapelitic rocks, and Fe-oxides in Precambrian metasandstones (SISO), (ii) vein-type Fe-carbonate and oxides composed of mainly siderite, ankerite and hematite including barite in Lower–Middle Cambrian metacarbonates of the Çaltepe Formation (HICO), (iii) karstic Fe-oxides and hydroxides essentially in the Lower–Middle Cambrian metacarbonates and the unweathered Fe-carbonates (KIO). The latter type is more widespread and located at the upper parts of the most important mineable iron deposits like Attepe deposit.
Oxygen-, carbon-, sulfur- and strontium-isotope studies have been performed on siderites and barites in the vein-type ores, and on calcites in the recrystallized Çaltepe Limestones to investigate the sources and formation mechanism of primary ore-forming constituents. The δ13C values of siderites and calcites in limestones of the Çaltepe Formation range from −10.10‰ to −8.20‰, and from −0.8‰ to 2.30‰. Both carbonate minerals show δ18O values between 17.50–18.30‰ and 16.20–23.00‰, respectively. The δ13C and δ18O isotopic variations do not indicate any direct or linear relations between siderites and limestones. However, it is possible that the carbon and oxygen isotopic compositions of carbonate minerals could be changed to some extent, when limestones were subjected to hydrothermal processes or thermal alterations during metamorphism.
The isotopic values of barites display 32.40–38.30‰ for δ34S and 12.20–14.70‰ for δ18O. The strontium isotope ratios (0.717169–0.718601) of barites and the sulfur isotope compositions of barites and pyrites suggest that there are no direct linkages of ore-forming compounds neither with a magmatic source nor with sedimentary pyrite formations in the Precambrian bituminous shales of the Attepe formation.
According to the field observations and the stable isotope data, siderites and ankerites should be formed by interaction between iron-rich hydrothermal fluids and Çaltepe limestones, whereas isotope ratios of barites indicate that they were formed by mixing of sulfur-rich meteoric waters and deeply circulated hydrothermal solutions. 相似文献
10.
Ayhan Gurbuz 《Environmental Earth Sciences》2011,64(3):883-892
A new simplified method based on one-dimensional displacement theory and 2-D finite element (FE) analysis was developed to
predict the vertical displacement behavior of a concrete-faced rockfill dam. The FE analyses were carried out at the end of
construction (EOC) and the end of first filling of reservoir. The proposed method was calibrated by using continuously monitored
vertical displacement of the dam’s body to determine the mobilized modulus of elasticity of the rockfills at the EOC. The
prediction capability of the method was demonstrated using field measurements against the findings from the 2-D FE analysis
simulating characteristics of construction stages of the dam. The validity of the method was also examined on another membrane-faced
rockfill dam by comparing the geodetic measurements of vertical displacement measurements of the dam’s body with the calculated
vertical displacements from 2-D FE analysis at the EOC. 相似文献